In many integrated circuits (ICs), a net provides an electrical connection between a driver pin and a sink pin located away from the driver pin. A net is often routed using metal layers above the driver pin and the sink pin to avoid other circuit elements between the driver pin and the sink pin.
Because signal delays and susceptibility to electromigration (EM) are both affected by net resistance, nets are sometimes routed using metal widths that are wider than those defined by a set of default rules, thereby reducing net resistance. Such non-default rule (NDR) routing of net components results in increased area requirements as compared to nets routed in accordance with the set of default rules, especially if the NDR routing is applied to an entire net.
Like reference symbols in the various drawings indicate like elements.